Vegetation of mesic hay meadows and pastures in the Asiago Plateau (south-eastern Prealps, Veneto, Italy)

Study area

The Asiago Plateau extends for over 600 km² in the southeastern Italian Prealps and ranges from about 300 m to over 2,300 m a.s.l. According to the SOIUSA classification of the Alps (Marazzi, 2006), the mountain area belongs to the Venetian Prealps and is included in the Vicenza Prealps subsection. The area is separated from the Lagorai Chain by the Valsugana to the North, it borders the Grappa Massif to the East and the Tonezza Plateau to the West (Figure 1). The stratigraphic sequence consists of carbonate rocks: outcrops of Main Dolomite, Calcari Grigi Group, Rosso Ammonitico Veronese and Maiolica are widespread in the survey areas (Barbieri & Grandesso, 2007). The Asiago Plateau can be subdivided into four main geomorphological sub-units (Pellegrini & Sauro, 1994): mown meadows are in the southern tectonic escarpment and especially in the central basin, whereas pastures spread in the lower belt of the northern plateau. As regards mown meadows, Aremonio-Fagion is the reference alliance: potential natural forest vegetation includes mixed common ash-beech (cf. Hacquetio-Fagetum) and hop hornbeam-woods (Quercion pubescenti-petraeae) in the tectonic escarpment, whereas Dentario-Fagetum can be considered the potential vegetation in the central basin. Low altitude pastures develop where high mountain Fagus-woods or Abies-Fagus mixed forests are, while at high altitudes natural disappearence of Fagus is being supplanted by increasing conifers (Picea, Larix) (cf. Homogyno sylvestris-Piceetum).

Figure 1:

According to the Worldwide Bioclimatic Classification System (Rivas-Martínez et al., 2011), the central basin of the Asiago Plateau belongs to the temperate-oceanic bioclimate, upper supra-temperate thermotype, lower hyperhumid ombrotype.

Data analysis

The vegetation of hay meadows and cattle summer grazing areas in the Asiago Plateau was studied according to the phytosociological method (Braun-Blanquet, 1964). This analysis included 114 original relevés, supplemented by 12 previously published relevés dealing with mown Arrhenatherum elatius meadows (Buffa et al., 1995). Thus, the whole data set formed a matrix of 126 relevés by 345 taxa. Location, date and geographical coordinates of original relevés and source of the published ones are listed in Appendix 1. Appendix 3 provides a relevé we did not include in the matrix because we recorded only a single stand of the coenosis which it represents (Rumicetum alpini). In multivariate analyses some taxa were considered as aggregates, namely: Achillea millefolium, Alchemilla vulgaris, Anthoxanthum odoratum (A. odoratum + A. alpinum), Centaurea nigrescens, Leucanthemum vulgare, Festuca rubra (F. rubra + F. nigrescens), Lotus corniculatus (L. corniculatus + L. alpinus). It is likely that misidentifications led to attribute to Luzula alpina specimens belonging to L. exspectata which was not distinguished (see Bačič et al., 2019). Cover values meet the Braun-Blanquet scale but with Barkman et al.’s modification (1964) regarding 2a and 2b scores. The species scores were converted in the corresponding percentage values according to Lepš & Hadincová (1992) and Gigante et al. (2012) as concerns 2a and 2b scores; the same data transformation type was chosen for the subset of mat-grass sward matrix (38 relevés by 198 taxa) that included also 11 published relevés occurring in the study area (Giovagnoli & Tasinazzo, 2014). In both cases data were subjected to hierarchical agglomerative Q-mode clustering according to the unweighted pair-group method (UPGMA) on a percentage difference (Bray-Curtis) dissimilarity matrix with log-transformed values to satisfy the condition of computing in an euclidean space (Borcard et al., 2018). The synthetic tables we obtained as regards mat-grass swards, Anthryscus sylvestris-rich meadows and mountain to high-mountain Festuca rubra agg. pastures were put in comparisons with selected synthetic tables from prealpine, alpine or central European territories to reach a correct phytosociological interpretation or delimitation of found plant communities (Appendix 2). In these cases, chord distance matrices (Nardus swards: 21 by 540; A. sylvestris meadows: 6 by 204; F. rubra pastures: 24 by 471) underwent UPGMA clustering method, after we had aggregated some related taxa. Statistical analyses were carried out using R (R Core Team, 2025). Similarity matrices and cluster analysis were performed using the vegan R package (Oksanen et al., 2022). With few exceptions (Campanula witasekiana Vierh., Carduus defloratus subsp. tridentinus (Evers) Ladurner, Phyteuma zahlbruckneri Vest, Rhinanthus freynii (Sterneck) A.Kern. ex Fiori, R. alectorolophus (Scop.) Pollich), taxonomic nomenclature follows the online flora Euro+Med (2025). Syntaxonomic nomenclature of higher syntaxa follows the EuroVegChecklist, EVC (Mucina et al., 2016; FloraVeg.EU 2025).

Alchemillo hybridae-Poetum supinae Aichinger 1933 corr. Oberd. 1971

• Local diagnostic species. Ochlopoa supina, Veronica serpyllifolia, Barbarea bracteosa, Ochlopoa annua.

• Floristic composition. The association is characterised by the large dominance of Ochlopoa supina which encompasses most of stand biomass (Table 1). It looks like a dwarf-grass pasture where most of more frequent species are creeping hemicryptophytes (Trifolium repens, Veronica serpyllifolia, Ranunculus repens) contributing to its compact appearance. Since only few species tolerate the conditions, the species number per relevé is low (13; sd: 2.4).

• Syntaxonomy. The association was first described by Aichinger (1933) with Ochlopoa supina, Alchemilla hybrida and Veronica serpyllifollia as character species. Apart from the correction of Alchemilla hybrida with A. vulgaris coll., the diagnostic species remained quite similar in the following contributions from various European countries (Oberdorfer, 1993; Poldini & Oriolo, 1995a; Hájková et al., 2010), underlying a certain stability of the association. This is also the case of the Asiago Plateau stands which are enriched with Barbarea bracteosa, a Mediterranean orophyte locally occurring in vegetation typologies affected by intensive grazing nearby cattle barns. The assignment to the alliance level has been differently interpreted: Oberdorfer (1993) attributed the association to Polygono-Coronopodion (as Polygonion avicularis), which yet includes therophyte-rich vegetation, Ellmauer & Mucina (1993) assigned it to Poion supinae, whereas Czech authors (Chytrý, 2010) classified it in Cynosurion giving the absence of subalpine and alpine species in Czech stands. Despite the low presence and frequency of character species, our original stands are anyway referred to Poion supinae because of ecological features and in accordance with the other available sources from Alpic provenances (Ellmauer & Mucina, 1993; Poldini & Oriolo, 1995a; https://www.e-veg.net/app/13089). Species of Poo alpinae-Trisetetalia order are well-represented.

• Synecology. Heavy trampling and soil compaction cause severe, selective pressure that drives the occurrence of resistant species and the development of the zoogenic coenosis. This creates small-size turfs nearby livestock shelters, especially cattle, and their watering sites, along paths to barns, in the high mountain belt at an altitude of 1,600–1,800 m a.s.l., where flat sites promote positive water balances and organic nutrient inputs thanks to livestock excrement.

• Synchorology. It spreads in all main temperate European mountain ranges (www.e-veg.net/app/13089). As regard Italy, the only published relevés come from Friuli region (Poldini & Oriolo, 1995a). The occurrence of largely prevalent number of Salicetea herbaceae species and the absence of those tolerant of heavily trampled soils, except Ochlopoa supina, as well as Molinio-Arrhenathereta ones suggest that relevés from Dolomites in Pignatti & Pignatti (2016) may be referred to other associations, as discussed by the authors themselves (cf. Poo-Cerastietum).

• EU reference habitat. None.

• Conservation Status, Pressures, and Threats. Because of its origin, conservation problems as well as pressures and threats are not relevant factors.

Mat-grass swards

Original mat-grass stands were first compared with already published natural, subalpine Nardus-rich grasslands coming from the same study area (Giovagnoli & Tasinazzo, 2014). According to the classification, original relevés do not merge with the published ones which remain well separated and form the cluster representing Sieversio-Nardetum (Figure 3). Based on this result as well as on ecological considerations, new data were classified into two communities we combined in Table 2: Festuca stricta-Nardus community (two relevés: 82, 83) and Homogyno-Nardetum (25 relevés).

Figure 3:

Festuca stricta/sulcata-Nardus community

• Local diagnostic species (in comparison with the other mat-grass swards). Bromopsis erecta subsp. erecta, Festuca stricta subsp. sulcata, Thymus pulegioides.

• Floristic composition. Comparison of original and already published relevés of Nardetum strictae s. lat. from the study area highlights that relevés 82 and 83 are differentiated by a high proportion of thermophilous, dry grassland species of base-rich soils (Festuco-Brometea): Festuca stricta/sulcata, Bromopsis erecta, Briza media are some of the species with the highest cover values and frequencies (Table 2; Table 3). They blend with montane mat-grass pasture species (Nardus stricta, Festuca nigrescens, Hypericum maculatum, partly Luzula campestris) and mesic meadow ones (Phlaeum rhaeticum, Crocus vernus/albiflorus). Subalpine calcicolous pasture species are very sporadic, whereas species of subalpine Nardus communities are almost completely absent. The mean number of species per relevé is 40.5 (sd: 2.1).

• Syntaxonomy. Due to the local rarity of the vegetation type, we were unable to find further sites to collect more relevés and attain a reliable syntaxonomical reference. A balanced occurrence of diagnostic species of Nardetea strictae and Festuco-Brometea characterises the two stands, as well as in Polygalo-Nardetum in Friuli (Poldini & Oriolo, 1997) and Arnico-Brometum in western Slovenia (Dakskobler, 2024). The two associations prevalently develop in the lower montane belt (from 700 to 1,250, mean 930, and from 640 to 1,130, mean 890, m a.s.l., respectively) and some relevés of Arnico-Brometum coming from the M. Matajur have a slightly stronger similarity with some relevés of Polygalo-Nardetum from the Italian side of the same mountain (Dakskobler, 2024). Comparison with the mat-grass swards from the south-eastern Alps confirms the close similarity between Polygalo-Nardetum and Arnico-Brometum (Figure 4; see also Dakskobler, 2024), despite the former is classified into Nardetea and the latter into Festuco-Brometea. The first association appears to differ from the second in the negative due to the absence of a large group of species including Dactylorhiza sambucina, Luzula campestris, Carlina acaulis, Leucanthemum ircutianum, Ranunculus polyanthemos s.l., Pilosella hoppeana, Carex pilulifera, Silene nutans, Serratula tinctoria, and others with lower frequencies, rather than for an original combination of diagnostic species. Stands from the study area are grouped with these two associations which share many frequent and diagnostic species of Polygalo-Nardetum or Violion caninae that are absent in our relevés: Polygala vulgaris, Genista tinctoria, Festuca filiformis, Viola canina, Hypochaeris maculata. On the contrary, mean higher elevation (1,490 m a.s.l.) characterising the stands from Asiago Plateau results in the occurrence of species that are more common in the subalpine belt, such as Phleum rhaeticum, Carex ornithopoda, Stachys alopecurus, Arabis ciliata and other. The community from the Asiago Plateau share with Arnico-Brometum the presence of Dactylorhiza sambucina, Luzula campestris and Carex pilulifera. The cluster also includes Danthonio-Nardetum, an association described from the Dolomites area by Pignatti & Pignatti (2014) who estimate it should be sought elsewhere in the Prealps, but Poldini & Oriolo (1997) regard it as a synonym for Polygalo-Nardetum. Danthonio-Nardetum develops in the montane belt, from (600) 1,200 to 1,500 m a.sl. (mean 1,264) and it is classified into Nardo-Agrostion alliance, whereas Polygalo-Nardetum belongs to Violion caninae. With the occurrence of the only one characteristic species Galium pumilum, and the presence of ingressive species Thymus pulegioides and Pimpinella saxifraga from Festuco-Brometea, the Violion caninae alliance is underrepresented in our two stands. On the other hand, the Nardo-Agrostion, which also encompasses the swards of Homogyno-Nardetum, is poorly represented too (Potentilla aurea). Based on the above conflicting considerations and the small number of available relevés, we prefer to classify the two relevés in the Festuca stricta/sulcata-Nardus community which is not assigned to any class.

• Synecology. These secondary pastures develop at a mean altitude of 1,490 (sd: 28) m a.s.l. in the upper montane belt, in sites of potential beech forests (Figure 5). Despite the rock carbonatic origin, soils show well engaged acidification processes probably because of high rainfall and suboceanic climate; slopes are facing South.

• Synchorology. Further data are needed.

• EU reference habitat. 6230*.

• Conservation Status, Pressures, and Threats. The conservation is affected by the small area occupied which is surrounded by intensive cattle and horse grazing.

Figure 4:

Figure 5: